Coated fabric and method of making the same



Patented May 10, 1932 UNITED STATES PATENT OFFICE DAVID CARNEGIE, JR., OF SPRINGFIELD, NEW JERSEY, ASSIGNOR TO DURATEX COR- PORATION, OF NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY COATED FABRIC AND METHOD OF MAKING THE SAME No Drawing.

This invention relates to a coated material and a method of coating, and more particularly to a coated fabric such as imitation leather and similar material and a method of coating by means of which the finished product may be made in considerably' less time and at less cost than has heretofore been accomplished. The invention relates specifically, to a coated fabric in which a composition is employed comprising a drying or a semi-drying oil' such as linseed, soya bean, china wood, perilla or menhaden or other suitable drying or semi-drying oil or a mixture of two or more of such oils which are modified, as hereinafter described, to alter the properties thereof so as to provide a suitable medium for the incorporation of nitro-cellulose or related materials to form a homogeneous admixture having certain novel properties in the finished product.

Linseed oil as a coating material or as an ingredient of a coating material has various desirable properties among which are its durability under the disintegrating influence of light and weathering, its high lustre, and its hard and resistant surface when applied to a fabric, for example. The raw oil or the boiled oils of commerce, however, have not heretofore been successfully or satisfactorily used in nitro-cellulose coating compositions, owing to undesirable peculiarities of the re sulting composition. Thus, although the raw oil may be mixed with nitro-cellulose in solution, there is a practical limiting ratio of S or 10 parts of oil to one of nitro-cellulose beyond which the mixture undergoes precipitation when larger proportions of nitro-cellulose are used. Furthermore, although the raw or unboiled oils may be mixed with nitro-cellulose in solution, the oil tends to exude from the coatings formed from such compositions, and in time the coating becomes hard and brittle, whereby the coated material is rendered unsuitable for use. Moreover, when the coating is applied in successive films to build up a coating of the requisite thickness, a time consuming ageing is required for each coating before the succeeding coating or film may be applied. Boiled linseed oils are also substantially immiscible with nitro-cellulose Application filed September 23, 1927. Serial No. 221,624.

solutions or are not miscible in sufiicient quantity or in sufficient proportion to obtain the desired flexibility and softness, which is apparently due to the fact that a polymerization takes place in the oil during the boiling step, and when the resulting material is employed as a coating composition, the resulting coating is hard and stiff and is liable to crack when the fabric is flexed.

These obstacles and disadvantages are overcome by my present invention, one object of which is to provide a coated fabric which is flexible and which will improve rather than deteriorate with age.

Another object of my invention is to provide a coated fabric, comprising nitro-cellulose and a modified drying oil in substantial proportion, in which the coating is substantially homogeneous, which does not exude oil, which has a permanent and lasting flexibility, and which may be made at a considerable less cost than other coated fabricsf Another object of the invention is to provide a coated fabric in which the coatings may be applied without waiting for the individual coats to age, or in other words, in which successive coats may be applied when each coat has been permitted to dry Without waiting for the coat to become aged injthe usual manner.

Another object of the invention is to provide a new and useful method for the coating of fabrics in which the coating material is modified or pre-a 'ed so as to avoid the usual ageing methocf in the application of successive coats in the maki-ngof an imitation leather or other coated fabric.

Vith these and other objects in View, the invention comprises the various features hereinafter more fully described and defined in the claims.

In my present invention a coating composition is formed of nitro-cellulose or equivalent material and a specially prepared drying oil, such as linseed oil which is modified under such conditions as not to materially polymerize the oilor otherwise to so change it as to render it immiscible in the requisite proportions with nitro-cellulose in solution in a suitable solvent. By means of the special treatment hereinafter fully-described, the nitro-cellulose apparently serves to hold the oil in unvarying proportions in the finished ,coating. In preparing this special oil, raw

below 250 C., thereby avoiding the high temperatures which cause substantial bimolecular polymerization of the oil.- The oxygenizing process is continued until a desired reaction has taken place as will be apparent from certain viscosity indications, as will hereinafter be fully described. This specially prepared oil is then mixed with a nitro-cellulose solution dissolved in a suitable solvent, such as an ethyl acetate solvent, the oil being preferably added to a previously prepared pyroxylin or nitro-cellulose solution to form a sufficiently fluid medium and is then applied to a fabric or other base to be coated in the usual manner. The reaction which occurs in the modified drying oil serves apparently to pre-age the coating material and successive coatings of the material may, therefore, be applied without intervening ageing.

In modifying the raw linseed oil to prepare the special oil of my process, air is preferably blown through the oil in fine streams while the oil is maintained at any suitable temperature preferably below approximately 250 C. until the oil attains the requisite degree of viscosity. A temperature of 250 C. is mentioned since experiment has demonstrated that materially above this temperature it becomes difficult to secure the desired degree of oxidation without producing a substantial amount of polymerization. The oil may be maintained if desired, at ordinary room temperature during this blowing 0r oxygenizing step, but by the use of an elevated temperature, the time of the oxidation is materially reduced. By maintaining the oil at a temperature somewhat below 250 C. the oil may be sutliciently oxidized in from six to twelve hours provided that the air is blown through the oil in suflicient volume and in sufliciently finely divided streams or ets.

As the oxygenizing reaction nears completion, the viscosity of the oil increases rapidly and the oil is sufiiciently treated when it strings slightly between the thumb and finger. The viscosity of the oil is. preferably tested by permitting a solid steel ball,

. onequarter of an inch 4) in diameter, to

.fall a distance of twelve (12") inches through the oil while maintained at a temperature of from 25 C. to 30 C. When the viscosity of the oil is such that from 2080 seconds is required for the ball to fall this distance through the oil, the product is found to have attained the desired properties, but

I preferably control the reaction so that aviscosity of from 60 to 75 seconds measured on this scale is attained. A product having a viscosity higher than 80 seconds may be employed for certain purposes, such as for admixture with other oils, but such products are, in general, undesirable. When the oil has been modified to the requisite extent without substantial polymerization, the product is ready for use in the coating composition either alone or with other oils.

The modified oil product may be mixed in any desired proportions with a nitro-cellulose solution in a suitable solvent to obtain a coating composition of any desired character. Stable coating compositions having a proportion of oil to nitro-cellulose of 15: 1 for example, may be prepared. A coating composition of a proportion of oil to nitrocellulose of 8 or 9 to 1, when employed as a coating is satisfactory, the film produced thereby being sufiiciently firm upon evaporation of the solvent to permit of immediately applying a succeeding coating of the composition.

In general, I prefer to use a proportion of four to five parts of my modified oil product to one of nitro-cellulose in a suitable solvent. Any suitable solvent for nitro-cellulose may be employed although I preferably use a solvent containing ethyl acetate, benzol and denatured alcohol in suitable amounts as may be required to dilute the solution to the requisite thinness for the coating desired. A typical solvent mixture may be made in the following proportions:

Per cent by weight Ethyl acetate 30 Benzol 30 Denatured alcohol 40 Pounds 20 oz. (15%) pyroxylin solution 100 Pigment ground in oil 1: 1'. 12

Modifiedoil product prepared as described 45 I The proportion of film forming substances to solvent may be varied to provide a coating composition or dope of the desired thinness and covering power forany particular coating to be made.

A suitable coating material may be also made according to the following formula:

Pounds 20 oz. pyroxylin solution 100 Blown castor oil -i 15 Ground color (1 oil: 1 pigment) Modified oil product prepared as above described";

In the case of this formula, the film-for1n-' While the ratio of oil to nitro-cellulose is much higher than that commonly employed in the case of castor oil, the film is nevertheless firm after evaporation of the solvent, and the material is, furthermore, pre-aged, or so modified in its properties that successive coats may be applied without the usual curing or ageing of the oil that is required when linseed oil compounds are used, in which case each coat must be aged or dried before a succeeding coating may be applied. The use of larger quantities of oil is advantageous in that the composition has better penetrating and anchoring qualities when applied to the fabric than compositions having less oil, and the resulting coating, furthermore, has a greater flexibility than a film or coating having less oil. The ability to apply successive films without ageing each one separately permits a coating to be built up to any desired weight with great economy in the time and equipment required for a given output.

The coating may be finished in a variety of ways to produce various types of imitation leather or similar coated fabrics. For instance a finish coating containing a reduce mount of pigment may be used, and the c ting may be embossed in any desired grain; a soup or finishing coat containing a reduced amount of oil may also be applied, if desired, in order to impart a high lustre to the surface. In this case, the various coating and finishing operations may be carried out with the same or even greater speed than in the manufacture of imitation leather with compounds of the usual type. While the film possesses adequate strength at the conclusion of the manufacturing operations, its strength and toughness increase on natural ageing until a maximum is reached after severalweeks.

Alternatively, a finish coating consisting of a varnish which requires curing at an elevated temperature maybe used,'in which case the goods may be festooned in a drying oven for a period of several hours and then embossed. In this case it is found that, coincidentally with the curing of the varnish, the film itself has attained substantially its maximum strength and toughness.

In either case, whether the condition of approximately maximum strength and toughness is attained in weeks by natural ageing, or whether it results from heataccelerated ageing in conjunction with the application of a varnish finish, the process of ageing is self-limiting, or in other words, the film, even after months of weathering does not reach the stage of hardness or brittleness.

The ageing of the coating may be accelerated, if desired, by the addition of a drier, such as manganese linoleate or cobalt linoleate, for example, which may be added to the coating composition shortly before its application to a fabric or other material to be coated. The addition of a drier to the coating composition is not essential, as will be understood by those skilled in the art, but may be found to be advantageous in that it causes the film to reach a condition of maximum strength and toughness in a short time; the addition of the material is of considerable advantage, however, in casesin which the proportion of oil to nitro-cellulose is greater than 4 1.

When the coating has partially aged, or has aged for about a week or two, for example, it is found not to be soluble in the usual solvents for nitro-cellulose, such as acetate or benzol solvent mixtures, for example. Coatings of pyroxylin-castor oil mixtures or mixtures of pyroxylin with other non-drying oils on the other hand, are soluble in pyroxylin solvents even after long ageing of the coating as is well known. The coating obtained by my invention is permanently flexible and has no tendency to become brittle on ageing; the coating has furthermore, the desirable properties of a high oil content coating, together with toughness, wearing qualities, and permanence unattainable with oils heretofore employed for coating compositions.

It is to be understood that while I referably employ raw linseed oil in the ma king .of my modified drying oil product, other drying oils or semi-drying oils may be employed either separately or in admixture; modified oils of this character have been found to form a permanently stable solution when mixed with cellulose nitrate solutions in suitable solvents, whereas, the ordinary highly polymerized boiled oils of commerce cause precipitation of cellulose nitrate when mixed in substantial proportions with cellulose nitrate solutions, and are not suitable, therefore, for this purpose.

A marked advantage of the use of my modified drying oil product over that obtained by pyroxylin castor oil mixtures, in-

heres in the fact that the modified oil product tends on ageing, to increase its adherence to the base aterial. The ordinary castor oil cellulose nitrate coating compositions, on the other hand, have an inherent property by which the adhesion of the coating on the base material is markedly reduced with natural ageing. In the preferred form of my invention, furthermore, in which the modified drying oil is admixed with cellulose nitrate, there are two film-forming materials, in the product which apparently combine in some way to form a homogeneous coating which unites firmly with the base material and produces a film of high stability and resistance to stripping, whereas in the usual castor oil pyroxylin product, the only film forming element is the pyroxylin material or cellulose nitrate there'n.

It is to be understood that various changes or modifications mav be made in my method and product as will be apparent to those skilled in the art, without departing from the spirit or scope of the invention as defined in the claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. A coated fabric having an insoluble coating comprising a blown unpolymerized drying oil and nitro-cellulose material in a ratio greater than 1: 1.

2. A coated fabric having a homogeneous coating comprising an unpolymerized oxidized drying oil and nitro-cellulose in a ratio greater than 1:1, said coating'being insoluble in nitro-cellulose solvent-s.

3. A coated fabric having a coating comprising a solution of a cellulose ester in an unpolymerized, blown and partly oxidized linseed oil in a ratio greater than 1 1, said coatingbeing insoluble in ethyl acetate.

4. A method of making coated fabrics which comprises modifying the properties of a drying oil by passing into contact therewith an oxygen containing gas until a nitrocellulosesolution becomessoluble therein or in substantially all proportions, admixing with said oil a nitro-cellulose solution in the proportion of oil to nitro-cellulose greater than 1: 1 and applying successive coatings to.

a fabric without ageing the individual coatings before applying each successivecoating.

5. A method of making coated fabrics which comprises oxygenizing a drying oil at a temperature below approximately 250 C.

' until nitro-cellulose solutions in a solvent lose greater than 121 and applying successive coatings to a fabric without ageing each coating before applying the succeeding coating until the desired thickness of coating is obtained. 6. A method of making coated fabrics which comprises blowing air in fine streams through a drying oil containing raw linseed oil atan elevated temperature below 250 C. until the oil becomes stringy, admixing said oil with a nitro-cellulose solution in the proportion of oil to nitro-cellulose greater than 1:1 and forming a homogeneous solution, ap plying said material in successive coatings to a fabric and permitting each coating to dry without ageing the coating before applying the next succeeding coating until the desired thickness is obtained.

7. A method of making coated fabrics which comprises blowing air through raw linseed oil until the properties of the oil are modified as indicated by a viscosity of between 20 and 80- seconds on the scale herein described, admixing the'modified oil with a nitro-cellulose solution in a solvent miscible with said oil to provide a coating material in which the proportion of nitro-cellulose to oil is greater than 1:1 and applying the resulting composition to a abric insuccessive coatings without ageing the individual coatings before applying the succeeding coatings until the desired thickness of coating is obtained, whereby the resulting coating is ultimately insoluble in ordinary solvents for nitro-cellulose.

8. A method of making coated' fabrics which comprises blowing air through a drying oil at atemperature below approximately 250 C. until the oil vattains a viscosity of between 20 and 80 seconds on the scale indicated, admixing the modified oil with a nitrocellulose solution to obtain a homogeneous solution in which the proportion of oil to nitro-cellulose is about 4 to 5 of oil to l of nitro-cellulose, adding a linoleate dryer to the said solution and applying the coating composition to a fabric in successive coats without ageing the under coats before the application of the succeeding coating.

9. A method of making coated fabrics which comprises blowing air through a drying oil containing raw linseed oil until the oil becomes modified as indicated by a viscosity of between substantially 20 and 80 seconds on the scale indicated herein, admixingthe said oil with a nitro-cellulose. solution to obtain a homogeneous admixture in which the proportion of oil to, nitro-cellulose is greater than 1 1 the solvent employed for the pyroxylin being miscible with said modified oil, adding a linoleate accelerator to said admixture, and applying said admixture to a fabric in successive coatings without ageing the under coatings before the application of the succeeding coat to obtain a pre-aged flexible product in which the coating isultimate ly insolubh a in the'usual solvents for nitrocellulose and in which no oil exudes from the coated surface.

10. A coated fabric having a coating comprising a solution of a collulose ester in an unpolymerized, blown and partly oxidized drying oil having a viscosity between 20 and 80 seconds on the scale indicated herein, the proportion of cellulose ester to drying oil being in a ratio greater than 1:1, said coating being insoluble in ethyl acetate.

11. A coated fabric having a coating comprising a solution of nitro-cellulose in an unpolymerized, blown and partly oxidized linseed oil having a viscosity between 20 and 80 seconds on the scale indicated herein, the proportion of nitrocellulose to linseed oil being in a ratio greater than 1 1, said coating being insoluble in ethyl acetate.

12. A method of making coated fabrics which comprises oxidizing a drying oil without substantial polymerization until the oil attains a viscosity between 20 and 80 seconds on the scale herein indicated, dissolving a cellulose ester and said oil in a common solvent and applying the resulting mixture to a backin %3. A method of forming a solid solution of cellulose ester in a drying oil which comprises partly oxidizing said drying oil by intimate contact with air at a temperature and for a time insuificient to effect substan- .tial polymerization of said oil, dissolving said oil and cellulose ester in a common solvent in the proportion of oil to nitro-cellulose not less than 1 1, and permitting the common solvent to evaporate. I

In testimony whereof, I aifix my signature,

' DAVID CARNEGIE, JR. 

